Baking Ambient Occlusion: Almost entirely black
To this day I don't know exactly what that checkbox &quot;Bake from Multires&quot; does. I had once read that it was a relic from old times (Blender 2.79 and older)...?
Anyway, you can bake the AO in a different way, with the Ambient Occlusion Node, and then bake it as &quot;Emit&quot;.
Baking Preparation:

Switch to Cycles, under Color Management, set View Transformation to &quot;Standard&quot; (to get a map with pure colors.)

In the Shading editor, switch to &quot;World&quot; and set the background color to pure white (#FFFFFF). That's the light for the AO map.

Turn off any other lights in the scene and make sure you render only the objects for that you want to bake the AO map. (&quot;Camera&quot; icon in the outliner.)



Baking:

Select the material of the object's that you want to bake. In the node editor, add an Ambient Occlusion node, and a Color Ramp and plug that in an Emitter node, and that into the material output. Adjust the Color ramp to get the desired shading of the AO map.
Add an Image Texture node and select it (= image for the baking result)



In Cycles, under Bake, chose Bake type &quot;Emit&quot;, leave &quot;Bake from Multires&quot; unchecked
Check the render settings, select the object, and hit bake!


Clean up:

Save the baked image
in Color Management, set View Transformation back to &quot;Filmic&quot;
Restore the light setup (World background, Lights)
Turn on, the rendering for the objects you want.